Parameterization of Northern Hemisphere volcanic activity since 1500

The effects of volcanic activity on climate are investigated using volcanism parameterizations. A new volcanic activity parameter, the Smithsonian volcanism index (SVI), was developed, based on the Smithsonian Institute historical volcano chronology of Simkin et al. (1981). The SVI parameter is compared with the dust veil index (DVI) of Lamb (1970, 1983) and the Crete ice core measurements of Hammer (1983); correlation analyses of these parameters reveal abrupt changes. The data also reveal that since 1700 AD there is a correlation between the ground-level air temperature in the Northern Hemisphere and SVI and ice core data; however, the DVI possibly overstimates this correlation.